<!DOCTYPE html
  PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!--
   Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
   Licensed under the Universal Permissive License v 1.0 as shown at http://oss.oracle.com/licenses/upl.
-->
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-us" lang="en-us">
<head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
<meta name="DC.Type" content="concept" />
<meta name="DC.Title" content="Using the Garbage Collections Page" />
<meta name="abstract" content="The Garbage Collections page contains information related to GC activity." />
<meta name="description" content="The Garbage Collections page contains information related to GC activity." />
<meta name="DC.Format" content="XHTML" />
<meta name="DC.Identifier" content="GUID-C12D23CE-E9DE-4BFA-A310-9AD5B6D835FD" />
<meta name="DC.Language" content="en-US" />

<meta http-equiv="Content-Style-Type" content="text/css" />
<meta http-equiv="Content-Script-Type" content="text/javascript" />
<title>Using the Garbage Collections Page</title>

<meta name="doctitle" content="Using the Garbage Collections Page&#xA;" />
<meta name="robots" content="noarchive" />
<link rel="copyright" href="http://oss.oracle.com/licenses/upl" title="Copyright" type="text/html" />

<link rel="contents" href="toc.htm" title="Contents" type="text/html" />
<link rel="prev" href="GUID-A45813E6-C32E-4916-966E-AE24992BB326.htm" title="Previous" type="text/html" />
<link rel="next" href="GUID-FEFBE854-3298-46A6-A149-8B48A62330D2.htm" title="Next" type="text/html" />
</head>
<body>
<div class="zz-skip-header"><a href="#BEGIN">Go to primary content</a></div>
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<col width="86%" /><col width="*" /><tr valign="bottom">
<td></td>


<td align="center">
<a href="GUID-A45813E6-C32E-4916-966E-AE24992BB326.htm">
<img src="./dcommon/gifs/leftnav.gif" alt="Previous" /><br />
<span class="icon">Previous</span>
</a>
</td>
<td align="center">
<a href="GUID-FEFBE854-3298-46A6-A149-8B48A62330D2.htm">
<img src="./dcommon/gifs/rightnav.gif" alt="Next" /><br />
<span class="icon">Next</span>
</a>
</td>
<td> </td>


</tr>
</table><div class="ind"><a id="GUID-C12D23CE-E9DE-4BFA-A310-9AD5B6D835FD" name="GUID-C12D23CE-E9DE-4BFA-A310-9AD5B6D835FD"></a><!-- End Header -->
<h1 id="JMCOH-GUID-C12D23CE-E9DE-4BFA-A310-9AD5B6D835FD" class="sect1">Using the Garbage Collections Page</h1>
<div><p>The <span class="bold">Garbage Collections</span> page contains information related to GC activity.</p>
<p>This page displays information about garbage collection and memory allocation in tables and graphs.</p>
<div class="section"><p class="subhead1">Using the Garbage Collections Page: Selections and Aspects</p><p>Use the drop-down menus at the top of the page to choose a selection and aspect if desired. Data from other pages can be saved to the selection drop-down menu by dragging an area of a chart (or selecting data from a table) and choosing <span class="bold">Store Selection</span> or <span class="bold">Store Selection and Set As Focused Selection</span> from the context menu.</p>
<div class="p">The following controls provide additional behavior:<ul style="list-style-type: disc;"><li><p><span class="bold">Show concurrent</span>: Show all events concurrent to the selected aspect.</p>
</li>
<li><p><span class="bold">Contained</span>: Only show events that are fully contained in the time range from the active selection aspect</p>
</li>
<li><p><span class="bold">Same threads</span>: Only show events in threads related to the active selection aspect.</p>
</li>
<li><p><span class="bold">Time Range</span>: Zoom to time range on relevant places on the page, or clear the time range zoom.</p>
</li>
</ul>
</div>
</div>
<!-- class="section" -->
<div class="section"><p class="subhead1">Using the Garbage Collections Page: Tables and Graphs</p><p>Table columns are labeled as follows:</p>
<div class="p"><ul style="list-style-type: disc;"><li><p><span class="bold">GC ID</span>: The garbage collection ID.</p>
</li>
<li><p><span class="bold">Cause</span>: The reason for triggering this garbage collection.</p>
</li>
<li><p><span class="bold">Collector Name</span>: The name of the garbage collector.</p>
</li>
<li><p><span class="bold">Longest Pause</span>: The longest individual pause during the garbage collection.</p>
</li>
<li><p><span class="bold">Sum of Pauses</span>: The total duration that Java execution was paused during the garbage collection.</p>
</li>
<li><p><span class="bold">Final References</span>: The number of final references.</p>
</li>
<li><p><span class="bold">Weak References</span>: The number of weak references.</p>
</li>
<li><p><span class="bold">Soft References</span>: The number of soft references.</p>
</li>
<li><p><span class="bold">Phantom References</span>: The number of phantom references.</p>
</li>
</ul>
Additional information is available in the following subtabs, which can be filtered for a specific Garbage Collection by selecting a GC from the adjacent table:<ul style="list-style-type: disc;"><li><span class="bold">Pause Phases</span>: Displays the pause events that occurred during the selected garbage collection as well as each event's duration, start time, and the thread it occurred in.</li>
<li><p><span class="bold">Metaspace</span>: Shows various metaspace statistics before and after the selected Garbage Collection</p>
</li>
</ul>
You can select any of the following to be displayed on the graph:<ul style="list-style-type: disc;"><li><span class="bold">Used Heap</span>: Memory allocated by objects on the heap.</li>
<li><p><span class="bold">Heap Space: Committed Size</span>: Size of the committed memory for the virtual space.</p>
</li>
<li><p><span class="bold">Heap Space: Reserved Size</span>: Size of the reserved memory for the virtual space.</p>
</li>
<li><p><span class="bold">Metaspace: Used</span>: Memory allocated by objects in the metaspace.</p>
</li>
<li><p><span class="bold">Metaspace: Committed</span>: Memory committed for the metaspace.</p>
</li>
<li><p><span class="bold">Metaspace: Reserved</span>: Memory reserved for the metaspace.</p>
</li>
<li><p><span class="bold">Longest Pause</span>: The duration of the longest GC pause.</p>
</li>
<li><p><span class="bold">Sum of Pauses</span>: The total duration of all GC pauses.</p>
</li>
<li><p><span class="bold">Pause Phases</span>: Phases of the garbage collection pauses.</p>
</li>
<li><p><span class="bold">Thread Activity</span>: Allows you to view the thread activity of a selected thread from the Pause Phases tab.</p>
</li>
</ul>
</div>
</div>
<!-- class="section" -->
<div class="section"><p class="subhead1">Using the Garbage Collections Page: Configuring Rules</p><p>You can set configuration attributes for the rules associated with this page by clicking the <span class="bold">Edit Configuration</span> icon.</p>
<p>The following options are available:</p>
<div class="p"><span class="bold">GC Pause Peak Duration</span><ul style="list-style-type: disc;"><li><p><span class="bold">GC pause warning limit</span>: The GC pause time needed to trigger a warning.</p>
</li>
</ul>
</div>
<div class="p"><span class="bold">GC Pauses</span><ul style="list-style-type: disc;"><li><p><span class="bold">GC pause ratio info limit</span>: Ratio between GC pauses and execution time over the set time window needed to trigger an info notice.</p>
</li>
<li><p><span class="bold">GC pause ratio warning limit</span>: Ratio between GC pauses and execution time over the set time window needed to trigger a warning.</p>
</li>
<li><p><span class="bold">GC pause time window size</span>: The time window size used when evaluating the rule.</p>
</li>
</ul>
</div>
<div class="p"><span class="bold">GCs Caused by GC Locker</span><ul style="list-style-type: disc;"><li><p><span class="bold">GC locker ratio limit</span>: Warning limit ratio between number of garbage collections caused by GC locker and total garbage collections.</p>
</li>
</ul>
</div>
<div class="p"><span class="bold">GCs Caused by Heap Inspection</span><ul style="list-style-type: disc;"><li><p><span class="bold">Heap inspection GC limit</span>: Warning limit ratio between number of heap inspection garbage collections and total garbage collections.</p>
</li>
</ul>
</div>
<div class="p"><span class="bold">GCs Caused by System.gc()</span><ul style="list-style-type: disc;"><li><p><span class="bold">System.gc() ratio limit</span>: Warning limit for ratio between <code>System.gc()</code> and total garbage collections.</p>
</li>
</ul>
</div>
</div>
<!-- class="section" -->
</div>
</div><!-- class="ind" --><!-- Start Footer -->
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<col width="86%" /><col width="*" /><tr valign="bottom">
<td><a href="http://oss.oracle.com/licenses/upl"><br />
<span class="copyrightlogo">Copyright&#160;&#169;&#160;2018, Oracle&#160;and/or&#160;its&#160;affiliates.&#160;All&#160;rights&#160;reserved.</span></a></td>


<td align="center">
<a href="GUID-A45813E6-C32E-4916-966E-AE24992BB326.htm">
<img src="./dcommon/gifs/leftnav.gif" alt="Previous" /><br />
<span class="icon">Previous</span>
</a>
</td>
<td align="center">
<a href="GUID-FEFBE854-3298-46A6-A149-8B48A62330D2.htm">
<img src="./dcommon/gifs/rightnav.gif" alt="Next" /><br />
<span class="icon">Next</span>
</a>
</td>
<td> </td>


</tr>
</table>

<!-- class="footer" -->
</body>
</html>